Women are being advised to walk in pairs at night and to stick to well-lit areas after a series of sex attacks near the university.

Three women, two aged 20 and one aged 19, have been sexually assaulted in the area in the last five days.

Police received a report of a serious sexual assault on the teenager at 4.30am today.

A cordon was put up around Gorsedd Gardens as crime scene investigators in white forensic outfits were called out.

The first was at around 3am on Sunday, when a 20-year-old woman was sexually assaulted near the Cardiff University main building, also in the Cardiff Civic Centre area.

The second incident took place in the early hours of Tuesday morning when another 20-year-old woman was sexually assaulted at a property on Cathays Terrace in the Cathays area. That was reported to South Wales Police just after 11.30am that day.

Arrest: One man has been arrested following the third attack but investigations are ongoing (Photo: Wales Online)

There were will be an increase in the number of unformed police on patrol in Cardiff this weekend in a bid to reassure the public.

However, South Wales Police refused to answer questions at a press conference held to provide updates on the series of sex attacks in the city.

They won't say if they're looking for anyone else in connection with the incidents but confirmed investigations are 'ongoing'.

Speaking at the press conference, head of Cardiff CID Detective Chief Inspector Richie Jones, said: “South Wales Police is continuing to investigate three sexual assaults in Cardiff which have happened in the last five days.

“We are treating these incidents extremely seriously and a full and through investigation is on-going, involving a large number of officers from a range of specialist departments.

“I can confirm that one man was arrested earlier today on suspicion of sexual assault and is currently in custody at Cardiff Bay Police Station.

“Despite this arrest, the investigation is very much on-going."

Warning: Women in the city are being advised to take precautions after the series of incidents (Photo: Wales Online)

“While there are similarities in terms of the locations, times and nature of the assaults, it is too early to say whether the same person is responsible," he continued.

“As a person has been arrested, I am limited in what information I can provide in terms of the incidents themselves.

“But what I can tell you is that just after 4.30am today South Wales Police received a report of a serious sexual assault on a 19-year-old woman in Cardiff. A police cordon has been removed from Gorsedd Gardens following a thorough forensic examination and search.

“We are also continuing to investigate two other sexual assaults - one in Cardiff Civic Centre during the early hours of Sunday, September 20 and a second at a house in Cathays Terrace during the early hours of Tuesday, September 22. Both of these victims are aged 20."

DCI Jones added: “Their welfare is an absolute priority for us and all three are being supported by specially trained officers.

“We are doing everything possible to bring those responsible to justice and would appeal for anyone with information to contact South Wales Police.”

Divisional Commander for Cardiff, Chief Superintendent Belinda Davies, advised women in the city to take precautions following the attacks.

She said: “All reports of sexual assault are taken extremely seriously and South Wales Police, together with the Police and Crime Commissioner, have been working with partners to make tackling this type of crime a priority.

“Cardiff is a safe city and I want to keep it that way."

Advice: Women should avoid walking alone at night, police say, and take taxis if need be (Photo: Wales Online)

“As our investigation continues we want people to be able to go out, enjoy themselves and feel safe in our capital city," she continued.

"Crimes like this are never the victims fault, but I would like to take this opportunity to remind everyone to follow basic safety advice so they keep themselves and their friends safe.

"Stay together when you’re out at night, drink responsibly and make sure you all go home together.